Needle bar for a sewing machine



Get. 23, 1956 P.A. KUNZ NEEDLE B'ARFVR A SEWING MACHINE filed oct. 2o, 1953 NEEDLE BAR FOR A SEWING MACHINE Paul Albert Kunz, Neuchatel, Switzerland, assignor to N. V. Fridor Fabrieken, The Hague, South-Holland, Netherlands, a company of the Netherlands Application October 20, 1953, Serial No. 387,231

2 Claims. (Cl. 112-225) The present invention relates to an improved needle bar for a sewing machine and is particularly concerned with the means for inserting, positioning and holding the needle accurately in its correct axial and angular operating position.

For facilitating the insertion of the needle into the needle bar and automatically positioning same in the correct position, a needle bar has already been proposed having a feed passage extending longitudinally therethrough from top to bottom and of a suitable size to permit a needle to pass therethrough from the upper to the lower end thereof, said feed passage and said needle preferably being so formed as to provide cooperating means for angularly positioning the needle in the bar. In addition such known needle bar has preferably means associated therewith for arresting positioning and securing in place at the lower end of the bar a needle fed through said feed passage.

The invention is particularly concerned with said latter means and has for its object to provide an improved construction thereof, permitting the needle to be more accurately and reliably positioned and secured in place, such construction moreover avoiding the risk of blunting or damaging the needle point when arresting the fall of the needle at the end of the feed passage, as is likely to occur in the case of `the known structure.

In order that such object shall be attained in a simple and eiiicient manner, the present invention primarily consists in the provision of a needle bar for a sewing machine comprising an axially disposed passage extending longitudinally therethrough and means associated with said needle bar adjacent its lower end for arresting a needle dropped through said feed passage by exerting thereon a lateral, progressively increasing braking pressure, such means, according to a further feature of the invention being preferably so designed as to also provide axial abutment means accurately defining the final operating position in which the needle is to be positioned and secured after having been arrested by said rst means.

The invention will be clearly understood from the following description of a certain embodiment illustrated by way of example only, in the accompanying drawing.

In said drawing:

Fig. l is a longitudinal sectional view of a needle bar according to such embodiment, taken along lthe line I-I in Fig. 3.

Fig. 2 is a corresponding sectional view showing the needle in its operating position.

Fig. 3 is a longitudinal sectional view along the line III-III in Fig. 1 with the needle clamped in this position.

Fig. 4 is a sectional view along lines IV-IV of Fig. 1.

Referring to these figures, 1 is a needle bar for a sewing machine, having an axially extending bore, lined with a tube 2 presenting a longitudinally extending needle feed passage 11 therethrough, the cross-section of which is of non circular shape to form a guide for the needle 3 having a shank 4 of complementary, cross sectional shape.

"nited States Patent O ICCv At its lower end the needle bar is provided with means for arresting a needle 3 when dropped through said feed passage from the top end thereof and for securing said needle in an accurately delined axial and angular position with respect to the needle bar, such means comprising a head 6 secured to the lower end of the needle bar by means of a set screw 7 and a pin 8 laterally projecting from the needle bar and engaging a notch 9 formed in said head.

As shown in the drawing, the head 6 is provided with an axially extending passage 10 of a cross sectional shape corresponding to that of the passage 11 and coaxially extending in the prolongation thereof.

The head 6 has a radially extending slot 12 formed therein, as by milling, and accommodating a flat pawl 13 pivotably mounted on a pin 14 secured in the opposite side walls of said slot, said pawl being acted upon by a ring shaped spring 15 arranged in a circumferential groove in the head 6 and urging the pawl into the position shown in Fig. 2 in which a shoulder 1S of said pawl abuts the side of the needle bar 1 thereby locating the pawl in a position in which the nose 16 of the pawl slightly projects into the passage 10. In addition thereto the head 6 is provided with a clamping screw 19 arranged in a plane at right angles to the plane containing the slot 12.

In practice the needle 3 is introduced into the feed passage 11 from the top end of the needle bar 1 which is completely free and readily visible so that the introduction of the needle is not hampered in any way and may be effected in accurately the correct angular position relative to the feed passage. Y

After introducing the needle 3 in the feed passage 11, the needle is released, so that it freely drops down throughout the entire length of the feed passage, to issue from the lower end thereof. At this location a conical portion 17 of the needle shank 4 engages the nose 16 of the pawl 13 thereby progressively forcing said pawl back against the action of the spring 15, thus causing the pawl to exert a gradually increasing pressure on the needle to progressively brake and arrest same in a position substantially as shown in Fig. 1.

In this position, the needle 3 is drawn down by hand in the direction of the arrow a, until its upper end passes the nose 16 of the pawl permitting same to snap behind the end of the needle under the inuence of the spring 15, such position being shown in Fig. 2. The nose 16 then constitutes a positioning abutment for determining the correct axial working position of the needle which position may be attained simply by exerting on the needle an upwardly directed force in the direction of the arrow b until the upper end engages the nose 16 of `the pawl, the needle being subsequently secured in this position by operating the clamping screw 19 by means of a suitable spanner (not shown) to be inserted in a hexagonal recess 20 in the head of said screw. The needle is then definitely clamped in the correct axial and angular position in the needle bar 1.

In the above a preferred embodiment of the needle bar according to the invention is described, but it will be understood that same permits of various modifications within the scope of the attached claims.

For example, the means for braking and arresting the needle may be constituted by any equivalent element, projecting into the feed passage and adapted to be forced back against spring action. This element for instance may be in the form of a spring wire formed into a loop, the Shanks of which are located in circumferential grooves in the needle bar, in such a manner that portions of such Shanks project into the feed passage 11, such spring also being adapted to constitute the abutment for locating the axial en-d position of the needle. In that case the clamping screw 19 `may "be arranged in the wall of the hollow A face of -the tube 2. In that case the abutment for de` termining the axialend position of the needle may be formed by a removable pin adapted to be passed through holes in the wallof the feed passage 11.

What I claim is:

1. In a needle bar for a sewing machine of the type which `includesl tubular means having an axial filling passage exten-ding therethrough for the introduction `from above of a freely falling needle `of `the type having a point at one end, .an enlarged shank portion at the opposite end, an intermediate thin portion of substantially uni form diameter and a sloping portion of gradually increasing diameter between .the intermedia-te portion and the shank, the improved `construction `comprising head means at the lower end of said tubular means the axialpassage of which is adapted to t closely about the shank end of said needle to hold the latter in operative position, said Vhead means including a radial slot extending outwardly from said axial passage spaced from the lower end of said head, an intercepting member movably mounted on said head means so as to move radially with `respect to said head means in said radial slot, said intercepting member including a nose portion which is adapted to move in 4and .out of said axial .passage when said intercepting member is moved, stop means on said intercepting member limiting the movement of said nose portion into said axial passage to a distance `which is short of the region through which the point and intermediate portion of a needle passes when the latter is falling through said axial passage, spring means normally urging said intercepting member inwardly with respect to the axial passage (whereby the nose portion of said intercepting `member presses only against a side of the sloping portion of a needle passing through the axial passage and is pushed out of its normal position by the shank of needle passing through the passage said nose portion of said intercepting member having a lower edge which acts as an abutment for the end of the shank of the needle when the latter has passed beyond said intercepting member,

2. In a needle bar as claimed in claim l, said intercepting memberconsist-ing-of a spring loaded pawl and means for p'ivotally mounting said pawl on said head means.

References Cited in the `tile of this patent UNITED STATES PATENTS 279,607 Simkins June 19, 1883 1,287,287 Garbus Dec. 10, 1918 1,779,238 Howard Oct. 21, 1930 

